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8354RE: [aprsisce] Re: Dead Reckoning (was: Instantaneous Course/Speed Vector)

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  • Fred Hillhouse
    Apr 1, 2011
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      What!?
       
      Yours isn't a HUD display yet?
       
      We need Lynn to mount a netbook in his vehicle! It will be an eye-opener sometimes.
       
      Best regards,
      Fred, N7FMH


      From: aprsisce@yahoogroups.com [mailto:aprsisce@yahoogroups.com] On Behalf Of Lynn W Deffenbaugh (Mr)
      Sent: Friday, April 01, 2011 08:11
      To: aprsisce@yahoogroups.com
      Subject: Re: [aprsisce] Re: Dead Reckoning (was: Instantaneous Course/Speed Vector)

       

      Ok, remind me not to be anywhere near the road on which you all are
      driving. The reason I haven't noticed this is that I toss the phone on
      the dash while in motion. Oh, and I might have DR turned off for power
      savings also.

      I think you've nailed the bug well, I suspect that I'm not recording the
      last beaconed course and speed for the purposes of DR, but am actually
      using the most current values from the GPS, but only for ME (obviously I
      don't have a more current course and speed for anyone else). I know I
      have the last beaconed position, but I really didn't think I was
      painting a station there, but I'm not surprised about the one at the
      moving end of the DR line, it makes sense.

      I'll see if I can remember to do something about this and then take my
      phone for a walk to test it.

      And remember, KEEP YOUR EYES ON THE ROAD! APRSISCE/32 doesn't do the
      "glass cockpit" thing yet! <grin>

      Lynn (D) - KJ4ERJ - Author of APRSISCE for Windows Mobile and Win32

      On 4/1/2011 7:52 AM, apenadragon wrote:

      > I actually witnessed this when driving home the other day, and
      happened to spot my DR icon moving in the opposite direction...
      >
      >
      it took me a few moments to sort out what was happening, I had an icon where the last beacon took place, I had my current location, and then I had this third icon at the end of the DR line, as my speed and direction changed the DR icon moved in relation to the last beaconed icon according to my CURRENT direction and speed... I imagine that if one were to go to a parking lot and drive in a large circle at the right speed they could get the DR icon to pass through a full 360 degree arc outside the actual current location....
      >
      >
      > yeah, i need more sleep because that sounds
      amusing to go try...
      >
      > My thought is that DR works on the latest
      information available to the program in relation to course and speed... when receiving another station all you have is the information that it beaconed, or that was calculated, depending on how APRSIS is configured, so the DR line goes in one direction until expiration or a new beacon is recieved.
      >
      >
      When DRing your self, the program has updated information on course and speed every 2-5 seconds, and changes the DR line accordingly... Travel at 30mph, and then as soon as the beacon goes out, count to 5 and then come to a stop as if stopping at a stop light, you'll watch your DR icon travel backwards. Just dont' hit anything.
      >
      > Adam
      > KC2ANT
      >
      > --- In
      href="mailto:aprsisce%40yahoogroups.com">aprsisce@yahoogroups.com, Randy Love<rlove31@...> wrote:
      >> Ah..
      >>
      >> Well,
      you have the added benefit of dynamic dead reckoning because of data
      >>
      direct from an attached GPS. :)
      >>
      >> Lynn can confirm this,
      but the laptop at Wye road is what your GPS is
      >> currently showing.
      The laptop at the top of the line is your last beaconed
      >> position.
      And then the software is using that position to base your dead
      >>
      reckoning projections, but appears that Lynn was sneeking and using
      >>
      up-to-date GPS data for the ME dead reckon calculations.
      >>
      >>
      That would explain what's happening. Lynn can confirm.
      >>
      >>
      Pretty sneaky.
      >>
      >> Randy
      >>
      WF5X
      >>
      >
      >
      >
      >
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